50W power amplification renewal composed of Fu-7 bile duct, Fu-7 50W Amplifier
Keywords: 50W power amplification renewal composed of Fu-7 bile duct
50W power amplifier composed of Fu-7 bile duct
Author: Wang De Chao
In the 1980s, the country has set off a boom of rural radio network. Our county production team is made up, the next two villages, at the junction of the two villages, a 9-meter high electric pole tie two 25W high-strokes, one to the village, another to the village, use one Taiwan 5W transistor three-machine broadcasts the full production team. Since the three-machine output power is small, the members who live in the distance can not understand the broadcast content.
The production team entrusted the author to engage in a 50W megaphone, at the time, at the time of 2,500 yuan, the production team was unable to bear the fee. Then, after the output stage of the original 5W three-machine, add a 50W power amplification renewal composed of two Fu-7. The circuit is shown in the figure above.
First, 50W power continuation work principle
The circuit consists of a pair of Fu-7 tubes (V1, V2), and the rated output power is 50W.
T1 is an input transformer, replaced with a 5 lamp tube radio power transformer, the input end is 6.3V wire windings; the secondary is the AC250VX2 high voltage winding, the center tap is connected to the FU-7 cathode, and the other two heads are respectively connected to the gate of V1, V2, respectively. Polar (2nd foot).
The signal is input from the primary filament winding. After booting, the signal is output from both ends of the high voltage winding, and the V1, V2 works.
R2, R3 is the gate limit current resistor to prevent large current from burning the electronic pipe gate.
T2 is 50W finished product (special equation FU-7) push-pull output transformer, the primary P high voltage end is connected to the V1, V2 screen, center tap + B pick + 610V; the secondary 8Ω output is connected to two 16Ω25W high-strokes.
DC high pressure is obtained by D1, D2, C1, C2 multiplier rectified filter by AC220V, and R4 is a bleedant resistor after D1, D2, C1 and C2 multiplier rectify.
The filaments of V1, V2 are powered by a 15W6.3V filament transformer T3, ZD is an indicator.
Due to the isolation of T1, T2, T3, the three-use chassis, the outer casing and the treble horn are not charged, and it is safe to use.
Second, Xinghuo 5W3-1 three-machine profile
The picture below shows the spoken part of the spinning 5W3-1 transistor three (radio, ambiguity, talking) machine.
K19 is a functional conversion switch, when the moving contact is turned to "1", it is a voice, the intercom (not used); when it goes to "2", it is a radio wave, and is a short wave when it is "3". B10 is a self-adjusted transformer, which is characterized by low loss and high efficiency. CZ2 is input into the microphone, and CZ1 is a pickup jack. The three-machine power supply is powered by a set of 12V voltage regulators.
Third, system connection and debugging
After the 50W power renewal is assembled, after the check is correct, the 8Ω output terminals of the T2 secondary level are connected to two 16025W of the treble speakers Y1, Y2, and the inputs A1, B1 are connected to the three-machine 8Ω output terminal A, B. The two are connected to a playing system. Turn on the power, enter "radio", "pick", "microphone" signal to the system, and the broadcast is normal, and the debug is over.
After long-term use, the system has the following advantages:
1. The output power is large (rated 50W, the maximum 70W) sound quality, the fidelity is high, and the function is complete.
2. Good isolation performance, bottom plate, casing without electricity, safe use.
3. Powerful investment: Power Continuator cost 155 yuan, three-purpose purchase fee of 150 yuan, the entire discourse system cost is 305 yuan, only 12% of the 50W electronic tube megaphone fee, and the function of the system, electrical performance It can be comparable to the 50W electronic tube megaphone.
For a production team that is extremely lacking at the time, the system is not a good combination, and it is still known for today's rural cable broadcasts.
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